text
stringlengths 105
4.57k
| label
int64 0
1
| label_text
stringclasses 2
values |
|---|---|---|
Third generation TSH assay is the current requirement for modern standards of care. At present, TSH testing in the United States is typically carried out with automated platforms using advanced forms of immunometric assay. Nonetheless, there is currently no international standard for measurement of thyroid-stimulating hormone. | 1 | Applied and Interdisciplinary Chemistry |
David Eusthatios Manolopoulos (born 14 December 1961) is a Professor of Theoretical Chemistry at University of Oxford. His research focuses on the computational modeling of the dynamics of elementary chemical reactions in the gas phase and quantum mechanical effects in chemical dynamics. His research highlights include work on path integral approach to molecular dynamics and chemical topics as diverse as fullerenes, ring polymers, reactive scattering, and more recently, the molecular and quantum mechanism of avian magnetoreception.
He was awarded the Marlow Award and the Corday–Morgan Prize. He has been involved with editing the Journal of Chemical Physics. | 0 | Theoretical and Fundamental Chemistry |
The main difference is in the reversal of these two types of neuromuscular-blocking drugs.
* Non-depolarizing blockers are reversed by acetylcholinesterase inhibitor drugs since non-depolarizing blockers are competitive antagonists at the ACh receptor so can be reversed by increases in ACh.
* The depolarizing blockers already have ACh-like actions, so these agents have prolonged effect under the influence of acetylcholinesterase inhibitors. Administration of depolarizing blockers initially produces fasciculations (a sudden twitch just before paralysis occurs). This is due to depolarization of the muscle. Also, post-operative pain is associated with depolarizing blockers.
The tetanic fade is the failure of muscles to maintain a fused tetany at sufficiently high frequencies of electrical stimulation.
* Non-depolarizing blockers have this effect on patients, probably by an effect on presynaptic receptors.
* Depolarizing blockers do not cause the tetanic fade. However, a clinically similar manifestation called Phase II block occurs with repeated doses of suxamethonium.
This discrepancy is diagnostically useful in case of intoxication of an unknown neuromuscular-blocking drug. | 1 | Applied and Interdisciplinary Chemistry |
Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of iron with an alloying element. In plain-carbon steel, austenite exists above the critical eutectoid temperature of 1000 K (727 °C); other alloys of steel have different eutectoid temperatures. The austenite allotrope is named after Sir William Chandler Roberts-Austen (1843–1902). It exists at room temperature in some stainless steels due to the presence of nickel stabilizing the austenite at lower temperatures. | 1 | Applied and Interdisciplinary Chemistry |
Conventional mirrors reverse the handedness of circularly polarized waves upon reflection. In contrast, a chiral mirror reflects circularly polarized waves of one handedness without handedness change, while absorbing circularly polarized waves of the opposite handedness. A perfect chiral mirror exhibits circular conversion dichroism with ideal efficiency. Chiral mirrors can be realized by placing a planar chiral metamaterial in front of a conventional mirror. The concept has been exploited in holography to realize independent holograms for left-handed and right-handed circularly polarized electromagnetic waves. Active chiral mirrors that can be switched between left and right, or chiral mirror and conventional mirror, have been reported. | 0 | Theoretical and Fundamental Chemistry |
From a thermodynamics point of view, at the melting point the change in Gibbs free energy ∆G of the substances is zero, but there are non-zero changes in the enthalpy (H) and the entropy (S), known respectively as the enthalpy of fusion (or latent heat of fusion) and the entropy of fusion. Melting is therefore classified as a first-order phase transition. Melting occurs when the Gibbs free energy of the liquid becomes lower than the solid for that material. The temperature at which this occurs is dependent on the ambient pressure.
Low-temperature helium is the only known exception to the general rule. Helium-3 has a negative enthalpy of fusion at temperatures below 0.3 K. Helium-4 also has a very slightly negative enthalpy of fusion below 0.8 K. This means that, at appropriate constant pressures, heat must be removed from these substances in order to melt them. | 0 | Theoretical and Fundamental Chemistry |
Radical reactions must be carried out under inert atmosphere as dioxygen is a triplet radical which will intercept radical intermediates. Because the relative rates of a number of processes are important to the reaction, concentrations must be carefully adjusted to optimize reaction conditions. Reactions are generally carried out in solvents whose bonds have high bond dissociation energies (BDEs), including benzene, methanol or benzotrifluoride. Even aqueous conditions are tolerated, since water has a strong O-H bond with a BDE of 494 kJ/mol. This is in contrast to many polar processes, where hydroxylic solvents (or polar X-H bonds in the substrate itself) may not be tolerated due to the nucleophilicity or acidity of the functional group. | 0 | Theoretical and Fundamental Chemistry |
Acid catalysis can be applied to hydrolyses. For example, in the conversion of cellulose or starch to glucose. For the case of ester hydrolysis and amides, it can be defined as an acid catalyzed nucleophilic acyl substitution reaction. Carboxylic acids can be produced from acid hydrolysis of esters.
Acids catalyze hydrolysis of nitriles to amides. Acid hydrolysis does not usually refer to the acid catalyzed addition of the elements of water to double or triple bonds by electrophilic addition as may originate from a hydration reaction. Acid hydrolysis is used to prepare monosaccharide with the help of mineral acids but formic acid and trifluoroacetic acid have been used.
Acid hydrolysis can be utilized in the pretreatment of cellulosic material, so as to cut the interchain linkages in hemicellulose and cellulose. | 0 | Theoretical and Fundamental Chemistry |
MECP2 duplication syndrome (M2DS) is a rare disease that is characterized by severe intellectual disability and impaired motor function. It is an X-linked genetic disorder caused by the overexpression of MeCP2 protein. | 1 | Applied and Interdisciplinary Chemistry |
The body is the main pressure containing structure of the valve and the most easily identified as it forms the mass of the valve. It contains all of the valve's internal parts that will come in contact with the substance being controlled by the valve. The bonnet is connected to the body and provides the containment of the fluid, gas, or slurry that is being controlled.
Globe valves are typically two-port valves, although three port valves are also produced mostly in straight-flow configuration. Ports are openings in the body for fluid flowing in or out. The two ports may be oriented straight across from each other or anywhere on the body, or oriented at an angle (such as a 90°). Globe valves with ports at such an angle are called angle globe valves. Globe valves are mainly used for corrosive or high viscous fluids which solidify at room temperature. This is because straight valves are designed so that the outlet pipe is in line with the inlet pipe and the fluid has a good chance of staying there in the case of horizontal piping. In the case of angle valves, the outlet pipe is directed towards the bottom. This allows the fluid to drain off. In turn, this prevents clogging and/or corrosion of the valve components over a period of time.
A globe valve can also have a body in the shape of a "Y". This will allow the construction of the valve to be straight at the bottom as opposed to the conventional pot type construction (to arrange bottom seat) in case of other valves. This will again allow the fluid to pass through without difficulty and minimizes fluid clogging/corrosion in the long term. | 1 | Applied and Interdisciplinary Chemistry |
Some basic conventions, such as (1) that animal/human homolog (ortholog) pairs differ in letter case (title case and all caps, respectively) and (2) that the symbol is italicized when referring to the gene but nonitalic when referring to the protein, are often not followed by contributors to medical journals. Many journals have the copyeditors restyle the casing and formatting to the extent feasible, although in complex genetics discussions only subject-matter experts (SMEs) can effortlessly parse them all. One example that illustrates the potential for ambiguity among non-SMEs is that some official gene names have the word "protein" within them, so the phrase "brain protein I3 (BRI3)" (referring to the gene) and "brain protein I3 (BRI3)" (referring to the protein) are both valid. The AMA Manual gives another example: both "the TH gene" and "the TH gene" can validly be parsed as correct ("the gene for tyrosine hydroxylase"), because the first mentions the alias (description) and the latter mentions the symbol. This seems confusing on the surface, although it is easier to understand when explained as follows: in this genes case, as in many others, the alias (description) "happens to use the same letter string" that the symbol uses. (The matching of the letters is of course acronymic in origin and thus the phrase "happens to" implies more coincidence than is actually present; but phrasing it that way helps to make the explanation clearer.) There is no way for a non-SME to know this is the case for any particular letter string without looking up every gene from the manuscript in a database such as NCBI Gene, reviewing its symbol, name, and alias list, and doing some mental cross-referencing and double-checking (plus it helps to have biochemical knowledge). Most medical journals do not (in some cases cannot) pay for that level of fact-checking as part of their copyediting service level; therefore, it remains the authors responsibility. However, as pointed out earlier, many authors make little attempt to follow the letter case or italic guidelines; and regarding protein symbols, they often will not use the official symbol at all. For example, although the guidelines would call p53 protein "TP53" in humans or "Trp53" in mice, most authors call it "p53" in both (and even refuse to call it "TP53" if edits or queries try to), not least because of the biologic principle that many proteins are essentially or exactly the same molecules regardless of mammalian species. Regarding the gene, authors are usually willing to call it by its human-specific symbol and capitalization, TP53, and may even do so without being prompted by a query. But the end result of all these factors is that the published literature often does not follow the nomenclature guidelines completely. | 1 | Applied and Interdisciplinary Chemistry |
Calciothermic reactions are metallothermic reduction reactions (more generally, thermic chemical reactions) which use calcium metal as the reducing agent at high temperature.
Calcium is one of the most potent reducing agents available, usually drawn as the strongest oxidic reductant in Ellingham diagrams, though the lanthanides best it in this respect in oxide processes. On the other hand, this trend does not continue to other compounds that are non-oxides, and for instance lanthanum is produced by the calciothermic reduction of the chloride, calcium being a more potent reducing agent than lanthanum involving chlorides.
Calciothermic processes are used in the extraction of metals such as uranium, zirconium, and thorium from oxide ores.
An interesting way of performing calciothermic reductions is by in-situ generated metallic calcium, dissolved in molten calcium chloride, as shown in the FFC Cambridge Process. | 1 | Applied and Interdisciplinary Chemistry |
With the sequencing of the genomes of a diverse array or model organisms, it became clear that the number of genes does not correlate with the human perception of relative organism complexity – the human proteome contains some 20 000 genes, which is smaller than some species such as corn. A statistical approach to calculating the number of interactions in humans gives an estimate of around 650 000, one order of magnitude bigger than Drosophila and 3 times larger than C. Elegans. As of 2008, only about <0.3% of all estimated interactions among human proteins has been identified, although in recent years there has been exponential growth in discovery – as of 2015, over 210 000 unique human positive protein–protein interactions are currently catalogued, and bioGRID database contains almost 750 000 literature-curated PPI's for 30 model organisms, 300 000 of which are verified or predicted human physical or genetic protein–protein interactions, a 50% increase from 2013. The currently available information on the human interactome network originates from either literature-curated interactions, high-throughput experiments, or from potential interactions predicted from interactome data, whether through phylogenetic profiling (evolutionary similarity), statistical network inference, or text/literature mining methods.
Protein–protein interactions are only the raw material for networks. To form useful interactome databases and create integrated networks, other types of data that can be combined with protein–protein interactions include information on gene expression and co-expression, cellular co-localization of proteins (based on microscopy), genetic information, metabolic and signalling pathways, and more. The end goal of unravelling human protein interactomes is ultimately to understand mechanisms of disease and uncover previously unknown disease genes. It has been found that proteins with a high number of interactions (outward edges) are significantly more likely to be hubs in modules that correlate with disease, probably because proteins with more interactions are involved in more biological functions. By mapping disease alterations to the human interactome, we can gain a much better understanding of the pathways and biological processes of disease. | 1 | Applied and Interdisciplinary Chemistry |
According to many chemical engineering professors, the first edition is much better than the second edition. There are many reasons in this regard; The second edition has been revised many times despite the fact that there are still many defects and typographical errors in many parts of the book. On account of revision to defects of the revised second edition book, the authors published "Notes for the 2nd revised edition of TRANSPORT PHENOMENA" on 9 Aug 2011. | 1 | Applied and Interdisciplinary Chemistry |
Harmonized standards for the accuracy and precision of laser diffraction measurements have been defined both by ISO, in standard ISO 13320:2020, and by the United States Pharmacopoeia, in chapter USP <429>. | 0 | Theoretical and Fundamental Chemistry |
The pharmacophore model for TRPV1 antagonists consists of three essential features: a hydrogen-bond acceptor, a hydrogen-bond donor, and a ring feature. In addition, the TRPV1 antagonists have been superimposed in such a way that they could fit in the volume of the TRPV1 pore. When the homology model is considered, appropriate interaction sites are found in the receptor pore. The hydrogen-bond acceptor on the ligand is proposed to interact with Tyr 667 (helix S6) on the receptor as a hydrogen-bond donor, and the hydrogen-bond donor on the ligand is proposed to interact with Tyr 667 on the opposite monomer of the tetramer on the receptor as a hydrogen-bond acceptor. The ring feature of the pharmacophore is proposed to fit in the hydrophobic space formed by the aromatic rings of the four Tyr 667 residues of the four monomers. Consistent with the critical role played by Tyr 667 in the interaction with key elements of the TPRV1 antagonist pharmacophore, site-directed mutagenesis studies have shown that exchanging this tyrosine for alanine in the rat TRPV1 receptor abolishes functional activity of TRPV1. The lipophilic end in antagonist is varied in character and volume and interacts with the lower end of transmembrane helices S5 and S6. Because the intracellular ends of these helices extend past the membrane, they are likely to be flexible and may be part of the channel opening and closing process. The combined use of a pharmacophore model, assembled from highly optimized TRPV1 antagonists, with a homology model of the protein has enhanced understanding of the observed structure–activity relationships of many series of current TRPV1 antagonists, and should be useful in the discovery of new classes of antagonists. | 1 | Applied and Interdisciplinary Chemistry |
In chemistry, a nitrene or imene () is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and univalent, so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded electrons. It is therefore considered an electrophile due to the unsatisfied octet. A nitrene is a reactive intermediate and is involved in many chemical reactions. The simplest nitrene, HN, is called imidogen, and that term is sometimes used as a synonym for the nitrene class. | 0 | Theoretical and Fundamental Chemistry |
MgCu can react with boron or its oxide to form magnesium borides. It can also react with magnesium hydride to produce orthorhombic MgCu, liberating hydrogen. | 1 | Applied and Interdisciplinary Chemistry |
The connection between plant productivity and biodiversity is a significant topic in ecology, although it has been controversial for decades. Both productivity and species diversity are constricted by other variables such as climate, ecosystem type, and land use intensity. According to some research on the correlation between plant diversity and ecosystem functioning is that productivity increases as species diversity increases. One reasoning for this is that the likelihood of discovering a highly productive species increases as the number of species initially present in an ecosystem increases.
Other researchers believe that the relationship between species diversity and productivity is unimodal within an ecosystem. A 1999 study on grassland ecosystems in Europe, for example, found that increasing species diversity initially increased productivity but gradually leveled off at intermediate levels of diversity. More recently, a meta-analysis of 44 studies from various ecosystem types observed that the interaction between diversity and production was unimodal in all but one study. | 0 | Theoretical and Fundamental Chemistry |
Compared to amines, amides are very weak bases. While the conjugate acid of an amine has a pK of about 9.5, the conjugate acid of an amide has a pK around −0.5. Therefore, compared to amines, amides do not have acid–base properties that are as noticeable in water. This relative lack of basicity is explained by the withdrawing of electrons from the amine by the carbonyl. On the other hand, amides are much stronger bases than carboxylic acids, esters, aldehydes, and ketones (their conjugate acids pK's are between −6 and −10).
The proton of a primary or secondary amide does not dissociate readily; its pK is usually well above 15. Conversely, under extremely acidic conditions, the carbonyl oxygen can become protonated with a pK of roughly −1. It is not only because of the positive charge on the nitrogen but also because of the negative charge on the oxygen gained through resonance. | 0 | Theoretical and Fundamental Chemistry |
The advantage of OM over traditional mapping techniques is that it preserves the order of the DNA fragment, whereas the order needs to be reconstructed using restriction mapping. In addition, since maps are constructed directly from genomic DNA molecules, cloning or PCR artifacts are avoided. However, each OM process is still affected by false positive and negative sites because not all restriction sites are cleaved in each molecule and some sites may be incorrectly cut. In practice, multiple optical maps are created from molecules of the same genomic region, and an algorithm is used to determine the best consensus map. | 1 | Applied and Interdisciplinary Chemistry |
The structure of histatin is unique depending on whether the protein of interest is histatin 1, 3 or 5. Nonetheless, histatins mainly possess a cationic (positive) charge due to the primary structure consisting mostly of basic amino acids. An amino acid that is crucial to histatin's function is histidine. Studies show that the removal of histidine (especially in histatin 5) resulted in reduction of antifungal activity. | 1 | Applied and Interdisciplinary Chemistry |
* Generically: Rg + X + hν → RgX + X, where Rg is a rare gas and X is a halogen
* Ba...FCH + hν → BaF + CH
*K + CHI → KI + CH | 0 | Theoretical and Fundamental Chemistry |
Iron plantations were rural localities emergent in the late-18th century and predominant in the early-19th century that specialized in the production of pig iron and bar iron from crude iron ore.
Such plantations derive their name from two sources. First, because they were nearly self-sufficient communities despite an almost singular focus on the production of iron to be sold on the market, and second, because of the large swaths of forest and land necessary to provide charcoal fuel and ore for their operations.
The first plantations stretched across the Northeast, Midwest, and Southern United States, "the chief charcoal iron producing states [being] Pennsylvania, Ohio, New York, Virginia, Connecticut, Maryland, Missouri, Tennessee, and Kentucky." Many produced raw materials used in the American Revolution or to be exported to England.
For the rest of the 19th century, however, only locations that adopted new technologies first introduced by competing coal- and coke-powered smelters in the rapidly industrializing field persisted. | 1 | Applied and Interdisciplinary Chemistry |
Arslantepe probably participated in the metal and ore trade between the areas north and south. To the north were the metal-rich areas of the Black Sea coast; ores and metals from there were traded to Upper Mesopotamia in the south. Already during the older Arslantepe VII period, metal objects could be found with a signature of ores from near the Black Sea coast. This makes it probable that some Transcaucasian groups would have been present at Arslantepe already in the fourth millennium.
Also some of the metal artefacts from the “Royal Tomb” clearly belong to Kura–Araxes culture manufacturing traditions, and the metal analysis even shows provenance from northern Caucasus. All this indicates that the expansion of Kura–Araxes culture to wider areas may have been prompted in part by a trade of ores and metals. | 1 | Applied and Interdisciplinary Chemistry |
Non-ionic detergents are characterized by their uncharged, hydrophilic headgroups. Typical non-ionic detergents are based on polyoxyethylene or a glycoside. Common examples of the former include Tween, Triton, and the Brij series. These materials are also known as ethoxylates or PEGylates and their metabolites, nonylphenol. Glycosides have a sugar as their uncharged hydrophilic headgroup. Examples include octyl thioglucoside and maltosides. HEGA and MEGA series detergents are similar, possessing a sugar alcohol as headgroup. | 0 | Theoretical and Fundamental Chemistry |
Several journals publish papers related to chemistry education. Some journals focus on particular education levels (schools vs. universities) while others cover all education levels. Journal articles range from reports on classroom and laboratory practices to educational research.
* Australian Journal of Education in Chemistry: Published by the Royal Australian Chemical Institute. Covers both school and university education.
*Chemical Education Journal (CEJ): Covers all areas of chemical education.
* Chemistry Education Research and Practice (CERP): Published by the Royal Society of Chemistry (RSC). Publishes theoretical perspectives, literature reviews, and empirical papers, including systematic evaluations of innovative practice.
* Education in Chemistry (EiC): Published by the Royal Society of Chemistry. Covers all areas of chemical education. (EiC is the RSC's educational magazine, whereas CERP is a peer-reviewed research journal).
* Foundations of Chemistry (FOCH): Published by Springer. Covers philosophical and historical aspects of chemical education.
* Journal of Chemical Education: Published by the Chemical Education Division of the American Chemical Society. Covers both school and university education.
*The Chemical Educator: Published by Springer-Verlag from 1996 to 2002. Covers all areas of chemical education.
* List of scientific journals in chemistry
Research in chemistry education is also published in journals in the wider science education field. | 1 | Applied and Interdisciplinary Chemistry |
Clinical trials involving new drugs are commonly classified into five phases. Each phase of the drug approval process is treated as a separate clinical trial. The drug development process will normally proceed through phases I–IV over many years, frequently involving a decade or longer. If the drug successfully passes through phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population. Phase IV trials are performed after the newly approved drug, diagnostic or device is marketed, providing assessment about risks, benefits, or best uses. | 1 | Applied and Interdisciplinary Chemistry |
In organic chemistry, a thial or thioaldehyde is a functional group which is similar to an aldehyde, , in which a sulfur (S) atom replaces the oxygen (O) atom of the aldehyde (R represents an alkyl or aryl group). Thioaldehydes are even more reactive than thioketones. Unhindered thioaldehydes are generally too reactive to be isolated — for example, thioformaldehyde, , condenses to the cyclic trimer 1,3,5-trithiane. Thioacrolein, , formed by decomposition of allicin from garlic, undergoes a self Diels-Alder reaction giving isomeric vinyldithiins. While thioformaldehyde is highly reactive, it is found in interstellar space along with its mono- and di-deuterated isotopologues. With sufficient steric bulk, however, stable thioaldehydes can be isolated.
In early work, the existence of thioaldehydes was inferred by trapping processes. For instance the reaction of with benzaldehyde was proposed to form thiobenzaldehyde, which forms a cycloadduct with the dithiophosphine ylides to form a ring. | 0 | Theoretical and Fundamental Chemistry |
During elongation, RNA polymerase slides down the double stranded DNA, unwinding it and transcribing (copying) its nucleotide sequence into newly synthesized RNA. The movement of the RNA-DNA complex is essential for the catalytic mechanism of RNA polymerase. Additionally, RNA polymerase increases the overall stability of this process by acting as a link between the RNA and DNA strands. New nucleotides that are complementary to the DNA template strand are added to the 3 end of the RNA strand. The newly formed RNA strand is practically identical to the DNA coding strand (sense strand or non-template strand), except it has uracil substituting thymine, and a ribose sugar backbone instead of a deoxyribose sugar backbone. Because nucleoside triphosphates (NTPs) need to attach to the OH- molecule on the 3 end of the RNA, transcription always occurs in the 5 to 3 direction. The four NTPs are adenosine-5-triphosphate (ATP), guanoside-5-triphosphate (GTP), uridine-5-triphosphate (UTP), and cytidine-5-triphosphate (CTP). The attachment of NTPs onto the 3' end of the RNA transcript provides the energy required for this synthesis. NTPs are also energy producing molecules that provide the fuel that drives chemical reactions in the cell.
Multiple RNA polymerases can be active at once, meaning many strands of mRNA can be produced very quickly. RNA polymerase moves down the DNA rapidly at approximately 40 bases per second. Due to the quick nature of this process, DNA is continually unwound ahead of RNA polymerase and then rewound once RNA polymerase moves along further. The polymerase has a proofreading mechanism that limits mistakes to about 1 in 10,000 nucleotides transcribed. RNA polymerase has lower fidelity (accuracy) and speed than DNA polymerase. DNA polymerase has a very different proofreading mechanism that includes exonuclease activity, which contributes to the higher fidelity. The consequence of an error during RNA synthesis is usually harmless, where as an error in DNA synthesis could be detrimental.
The promoter sequence determines the frequency of transcription of its corresponding gene. | 1 | Applied and Interdisciplinary Chemistry |
Esterification is the general name for a chemical reaction in which two reactants (typically an alcohol and an acid) form an ester as the reaction product. Esters are common in organic chemistry and biological materials, and often have a pleasant characteristic, fruity odor. This leads to their extensive use in the fragrance and flavor industry. Ester bonds are also found in many polymers. | 0 | Theoretical and Fundamental Chemistry |
Schoell was born in Germany, although the bulk of his career and adult life he has spent in the United States. Since retiring, Schoell resides in California. Aside from his research, Schoell has experience in winemaking. | 0 | Theoretical and Fundamental Chemistry |
If there are two spheres of radii and on the axis, and the spheres are distance apart, where is much smaller than and , then the force, , in the direction is
In this equation, , and is the normal force per unit area between two flat surfaces distance apart.
When the Derjaguin approximation is applied to depletion forces, and 0<h<2Rs, then the depletion force given by the Derjaguin approximation is
In this equation, is the geometrical factor, which is set to 1, and , the interfacial tension at the wall-fluid interface. | 0 | Theoretical and Fundamental Chemistry |
VIPA was proposed and named by Shirasaki in 1996. Prior to the publication in the paper, a preliminary presentation was given by Shirasaki at a conference. This presentation was reported in Laser Focus World. The details of this new approach to producing angular dispersion were described in the patent. Since then, in the first ten years, the VIPA was of particular interest in the field of optical fiber communication technology. The VIPA was first applied to optical wavelength division multiplexing (WDM) and a wavelength demultiplexer was demonstrated for a channel spacing of 0.8 nm, which was a standard channel spacing at the time. Later, a much smaller channel separation of 24 pm and a 3 dB bandwidth of 6 pm were achieved by Weiner in 2005 at 1550 nm wavelength range. For another application, by utilizing the wavelength-dependent length of the light path due to the angular dispersion of the VIPA, the compensation of chromatic dispersion of fibers was studied and demonstrated (Shirasaki, 1997). The compensation was further developed for tunable systems by using adjustable mirrors or a spatial light modulator (Weiner, 2006). Using the VIPA, compensation of polarization mode dispersion was also achieved (Weiner, 2008). Furthermore, pulse shaping using the combination of a VIPA for high-resolution wavelength splitting/recombining and a SLM was demonstrated (Weiner, 2010).
A drawback of the VIPA is its limited free spectral range due to the high diffraction order. To expand the functional wavelength range, Shirasaki combined a VIPA with a regular diffraction grating in 1997 to provide a broadband two-dimensional spectral disperser. This configuration can be a high performance substitute for diffraction gratings in many grating applications. After the mid 2000s, the two-dimensional VIPA disperser has been used in various fields and devices, such as high-resolution WDM (Weiner, 2004), a laser frequency comb (Diddams, 2007), a spectrometer (Nugent-Glandorf, 2012), an astrophysical instrument (Le Coarer, 2017), Brillouin spectroscopy in biomechanics (Scarcelli, 2008, Rosa, 2018, and Margueritat, 2020), other Brillouin spectroscopy (Loubeyre, 2022 and Wu, 2023), beam scanning (Ford, 2008), microscopy (Jalali, 2009), tomography imaging (Ellerbee, 2014), metrology (Bhattacharya, 2015), fiber laser (Xu, 2020), LiDAR (Fu, 2021), and surface measurement (Zhu, 2022). | 0 | Theoretical and Fundamental Chemistry |
In 1999, the virulence genes associated with Mycobacterium tuberculosis were identified through transposon mutagenesis-mediated gene knockout. A plasmid named pCG113 containing kanamycin resistance genes and the IS1096 insertion sequence was engineered to contain variable 80-base pair tags. The plasmids were then transformed into M. tuberculosis cells by electroporation. Colonies were plated on kanamycin to select for resistant cells. Colonies that underwent random transposition events were identified by BamHI digestion and Southern blotting using an internal IS1096 DNA probe. Colonies were screened for attenuated multiplication to identify colonies with mutations in candidate virulence genes. Mutations leading to an attenuated phenotype were mapped by amplification of adjacent regions to the IS1096 sequences and compared with the published M. tuberculosis genome. In this instance transposon mutagenesis identified 13 pathogenic loci in the M. tuberculosis genome which were not previously associated with disease. This is essential information in understanding the infectious cycle of the bacterium. | 1 | Applied and Interdisciplinary Chemistry |
*Patricia A. M. Huntington. [http://www.meteorman.org/Cape%20York.pdf Robert E Peary and the Cape York meteorites] | 1 | Applied and Interdisciplinary Chemistry |
Optical bonding is the use of an optical-grade adhesive to glue a glass to the top surface of a display. The main goal of optical bonding is to improve the display performance under outdoor environments. This method eliminates the air gap between the cover glass and the display. Moreover, anti-reflective coating is often used in optical bonding glass. The real problem for display readability in outdoor environments is not the displays brightness but its contrast. Contrast means the ratio of the white level to the black level; in other words, the contrast ratio of display means the difference of light intensity between the brightest white pixel and the darkest black pixel. The main purpose of optical bonding is to increase the displays contrast ratio by reducing the amount of reflected ambient light. | 0 | Theoretical and Fundamental Chemistry |
The mechanism of partially competitive inhibition is similar to that of non-competitive, except that the EIS complex has catalytic activity, which may be lower or even higher (partially competitive activation) than that of the enzyme–substrate (ES) complex. This inhibition typically displays a lower V, but an unaffected K value. | 1 | Applied and Interdisciplinary Chemistry |
Organic fluxes typically consist of four major components:
* Activators – chemicals disrupting/dissolving the metal oxides. Their role is to expose unoxidized, easily wettable metal surface and aid soldering by other means, e.g. by exchange reactions with the base metals.
** Highly active fluxes contain chemicals that are corrosive at room temperature. The compounds used include metal halides (most often zinc chloride or ammonium chloride), hydrochloric acid, phosphoric acid, citric acid, and hydrobromic acid. Salts of mineral acids with amines are also used as aggressive activators. Aggressive fluxes typically facilitate corrosion, require careful removal, and are unsuitable for finer work. Activators for fluxes for soldering and brazing aluminium often contain fluorides.
** Milder activators begin to react with oxides only at elevated temperature. Typical compounds used are carboxylic acids (e.g. fatty acids (most often oleic acid and stearic acid), dicarboxylic acids) and sometimes amino acids. Some milder fluxes also contain halides or organohalides.
* Vehicles – high-temperature tolerant chemicals in the form of non-volatile liquids or solids with suitable melting point; they are generally liquid at soldering temperatures. Their role is to act as an oxygen barrier to protect the hot metal surface against oxidation, to dissolve the reaction products of activators and oxides and carry them away from the metal surface, and to facilitate heat transfer. Solid vehicles tend to be based on natural or modified rosin (mostly abietic acid, pimaric acid, and other resin acids) or natural or synthetic resins. Water-soluble organic fluxes tend to contain vehicles based on high-boiling polyols - glycols, diethylene glycol and higher polyglycols, polyglycol-based surfactants and glycerol.
* Solvents – added to facilitate processing and deposition to the joint. Solvents are typically dried out during preheating before the soldering operation; incomplete solvent removal may lead to boiling off and spattering of solder paste particles or molten solder.
* Additives – numerous other chemicals modifying the flux properties. Additives can be surfactants (especially nonionic), corrosion inhibitors, stabilizers and antioxidants, tackifiers, thickeners and other rheological modifiers (especially for solder pastes), plasticizers (especially for flux-cored solders), and dyes. | 1 | Applied and Interdisciplinary Chemistry |
A separatory funnel, also known as a separation funnel, separating funnel, or colloquially sep funnel, is a piece of laboratory glassware used in liquid-liquid extractions to separate (partition) the components of a mixture into two immiscible solvent phases of different densities. Typically, one of the phases will be aqueous, and the other a lipophilic organic solvent such as ether, MTBE, dichloromethane, chloroform, or ethyl acetate. All of these solvents form a clear delineation between the two liquids. The more dense liquid, typically the aqueous phase unless the organic phase is halogenated, sinks to the bottom of the funnel and can be drained out through a valve away from the less dense liquid, which remains in the separatory funnel. | 0 | Theoretical and Fundamental Chemistry |
The Vlasov equation is a differential equation describing time evolution of the distribution function of plasma consisting of charged particles with long-range interaction, such as the Coulomb interaction. The equation was first suggested for the description of plasma by Anatoly Vlasov in 1938 and later discussed by him in detail in a monograph. | 1 | Applied and Interdisciplinary Chemistry |
Earths were defined by the Ancient Greeks as "materials that could not be changed further by the sources of heat then available". Several oxides were thought to be earths, such as aluminum oxide and magnesium oxide. It was not discovered until 1808 that these weren't elements but metallic oxides. | 0 | Theoretical and Fundamental Chemistry |
Solventogenesis is the biochemical production of solvents (usually acetone and butanol) by Clostridium species. It is the second phase of ABE fermentation. | 1 | Applied and Interdisciplinary Chemistry |
Overload, shocks and vibrations (bridges, roads submitted to intense truck traffic...) can induce mechanical stress and deformations in concrete structures and be responsible for the mechanical degradation of concrete. Beside the long-term drying shrinkage of concrete, pre-stressed and post-tensioned civil engineering structures (bridges, primary containment domes of nuclear power plants can also undergo slow concrete creep and deformation. | 1 | Applied and Interdisciplinary Chemistry |
The first example of cyclopropane being activated by a metal complex was reported in 1955, involving the reaction of cyclopropane and hexachloroplatinic acid. This reaction produces the polymeric platinacyclobutane complex Pt(CH)Cl. The bis(pyridine) adduct of this complex was characterized by X-ray crystallography.
The electrophile Cp*Ir(PMe)(Me)OTf reacts with cyclopropane to give the allyl complex:
:Cp*Ir(PMe)(Me)OTf + CH → [Cp*Ir(PMe)(η-CH)]OTf + CH | 0 | Theoretical and Fundamental Chemistry |
Some isotopes/nuclides are radioactive, and are therefore referred to as radioisotopes or radionuclides, whereas others have never been observed to decay radioactively and are referred to as stable isotopes or stable nuclides. For example, is a radioactive form of carbon, whereas and are stable isotopes. There are about 339 naturally occurring nuclides on Earth, of which 286 are primordial nuclides, meaning that they have existed since the Solar System's formation.
Primordial nuclides include 35 nuclides with very long half-lives (over 100 million years) and 251 that are formally considered as "stable nuclides", because they have not been observed to decay. In most cases, for obvious reasons, if an element has stable isotopes, those isotopes predominate in the elemental abundance found on Earth and in the Solar System. However, in the cases of three elements (tellurium, indium, and rhenium) the most abundant isotope found in nature is actually one (or two) extremely long-lived radioisotope(s) of the element, despite these elements having one or more stable isotopes.
Theory predicts that many apparently "stable" nuclides are radioactive, with extremely long half-lives (discounting the possibility of proton decay, which would make all nuclides ultimately unstable). Some stable nuclides are in theory energetically susceptible to other known forms of decay, such as alpha decay or double beta decay, but no decay products have yet been observed, and so these isotopes are said to be "observationally stable". The predicted half-lives for these nuclides often greatly exceed the estimated age of the universe, and in fact, there are also 31 known radionuclides (see primordial nuclide) with half-lives longer than the age of the universe.
Adding in the radioactive nuclides that have been created artificially, there are 3,339 currently known nuclides. These include 905 nuclides that are either stable or have half-lives longer than 60 minutes. See list of nuclides for details. | 0 | Theoretical and Fundamental Chemistry |
Sundström studied chemistry at Umeå University, obtaining his PhD in 1977. During his study, he visited Bell Labs and worked under Peter Rentzepis. Upon his return to Sweden, he started building the first ultrafast spectroscopy laboratory in Scandinavia at Umeå University and later at Lund University in Sweden. In 1994, Sundström was appointed professor of Chemical Dynamics and head of the Chemical Physics Department at Lund University. His group's research centers on the photophysics and photochemical processes in model systems of natural and artificial photosynthetic light harvesting, such as bacteriochlorophyll, carotenoids, transition metal complexes, organic and perovskite solar cells.
Sundström was an editor of the journal Chemical Physics Letters. | 0 | Theoretical and Fundamental Chemistry |
Glycosylation increases diversity in the proteome, because almost every aspect of glycosylation can be modified, including:
*Glycosidic bond—the site of glycan linkage
*Glycan composition—the types of sugars that are linked to a given protein
*Glycan structure—can be unbranched or branched chains of sugars
*Glycan length—can be short- or long-chain oligosaccharides | 0 | Theoretical and Fundamental Chemistry |
Solid state NMR (SSNMR), unlike LSNMR uses a solid state sample, for example a nitrogen vacancy diamond lattice rather than a liquid sample. This has many advantages such as lack of molecular diffusion decoherence, lower temperatures can be achieved to the point of suppressing phonon decoherence and a greater variety of control operations that allow us to overcome one of the major problems of LSNMR that is initialisation. Moreover, as in a crystal structure we can localize precisely the qubits, we can measure each qubit individually, instead of having an ensemble measurement as in LSNMR. | 0 | Theoretical and Fundamental Chemistry |
LSD historian Jay Stevens, author of the 1987 book Storming Heaven: LSD and the American Dream, has said that in the early days of its recreational use, LSD users (who were at that time mostly academics and medical professionals) fell into two broadly delineated groups. The first group, which was essentially conservative and exemplified by Aldous Huxley, felt that LSD was too powerful and too dangerous to allow its immediate and widespread introduction, and that its use ought to be restricted to the elite members of society—artists, writers, scientists—who could mediate its gradual distribution throughout society. The second and more radical group, typified by Richard Alpert and Timothy Leary, felt that LSD had the power to revolutionize society and that it should be spread as widely as possible and be available to all.
During the 1960s, this second group of casual LSD users evolved and expanded into a subculture that extolled the mystical and religious symbolism often engendered by the drug's powerful effects, and advocated its use as a method of raising consciousness. The personalities associated with the subculture included spiritual gurus such as Leary and psychedelic rock musicians such as the Grateful Dead, Jimi Hendrix, Pink Floyd, Jefferson Airplane and the Beatles, and soon attracted a great deal of publicity, generating further interest in LSD.
The popularization of LSD outside of the medical world was hastened when individuals such as author Ken Kesey participated in drug trials and liked what they saw. Tom Wolfe wrote a widely read account of the early days of LSDs entrance into the non-academic world in his book The Electric Kool Aid Acid Test, which documented the cross-country, acid-fueled voyage of Kesey and the Merry Pranksters on the psychedelic bus "Furthur" and the Pranksters later Acid Test LSD parties.
In 1965, Sandoz laboratories stopped its still legal shipments of LSD to the United States for research and psychiatric use, after a request from the U.S. government concerned about its use. By April 1966, LSD use had become so widespread that Time magazine warned about its dangers.
In December 1966, the exploitation film Hallucination Generation was released. This was followed by the films The Trip in 1967 and Psych-Out in 1968. | 1 | Applied and Interdisciplinary Chemistry |
The conventional understanding of pi stacking involves quadrupole interactions between delocalized electrons in p-orbitals. In other words, aromaticity should be required for this interaction to occur. However, several groups have provided contrary evidence, calling into question whether pi stacking is a unique phenomenon or whether it extends to other neutral, closed-shell molecules.
In an experiment not dissimilar from others mentioned above, Paliwal and coauthors constructed a molecular torsion balance from an aryl ester with two conformational states. The folded state had a well-defined pi stacking interaction with a T-shaped geometry, whereas the unfolded state had no aryl–aryl interactions. The NMR chemical shifts of the two conformations were distinct and could be used to determine the ratio of the two states, which was interpreted as a measure of intramolecular forces. The authors report that a preference for the folded state is not unique to aryl esters. For example, the cyclohexyl ester favored the folded state more so than the phenyl ester, and the tert-butyl ester favored the folded state by a preference greater than that shown by any aryl ester. This suggests that aromaticity is not a strict requirement for favorable interaction with an aromatic ring.
Other evidence for non-aromatic pi stacking interactions results include critical studies in theoretical chemistry, explaining the underlying mechanisms of empirical observations. Grimme reported that the interaction energies of smaller dimers consisting of one or two rings are very similar for both aromatic and saturated compounds. This finding is of particular relevance to biology, and suggests that the contribution of pi systems to phenomena such as stacked nucleobases may be overestimated. However, it was shown that an increased stabilizing interaction is seen for large aromatic dimers. As previously noted, this interaction energy is highly dependent on geometry. Indeed, large aromatic dimers are only stabilized relative to their saturated counterparts in a sandwich geometry, while their energies are similar in a T-shaped interaction.
A more direct approach to modeling the role of aromaticity was taken by Bloom and Wheeler. The authors compared the interactions between benzene and either 2-methylnaphthalene or its non-aromatic isomer, 2-methylene-2,3-dihydronaphthalene. The latter compound provides a means of conserving the number of p-electrons while, however, removing the effects of delocalization. Surprisingly, the interaction energies with benzene are higher for the non-aromatic compound, suggesting that pi-bond localization is favorable in pi stacking interactions. The authors also considered a homodesmotic dissection of benzene into ethylene and 1,3-butadiene and compared these interactions in a sandwich with benzene. Their calculation indicates that the interaction energy between benzene and homodesmotic benzene is higher than that of a benzene dimer in both sandwich and parallel displaced conformations, again highlighting the favorability of localized pi-bond interactions. These results strongly suggest that aromaticity is not required for pi stacking interactions in this model.
Even in light of this evidence, Grimme concludes that pi stacking does indeed exist. However, he cautions that smaller rings, particularly those in T-shaped conformations, do not behave significantly differently from their saturated counterparts, and that the term should be specified for larger rings in stacked conformations which do seem to exhibit a cooperative pi electron effect. | 0 | Theoretical and Fundamental Chemistry |
EAB sensors possess the potential to significantly advance our comprehension of metabolism, endocrinology, pharmacokinetics, and neurochemistry as valuable research tools. Specifically, these sensors offer improved resolution and more quantitative measurements of phenomena such as drug delivery, clearance, and the maintenance of metabolic homeostasis. Due to their capability for feedback control, E-AB sensors also present unprecedented opportunities to elucidate the correlation between, for instance, plasma drug levels and subsequent clinical or behavioral responses. The simultaneous measurements performed by E-AB sensors in multiple body locations can enhance our understanding of drug and metabolite transport within and between bodily compartments. Beyond in-body measurements, E-AB sensors could be beneficial for real-time monitoring in cell culture applications, ranging from small-scale (e.g., "organ on a chip") to industrial scale (e.g., monitoring industrial bioreactors). They have already demonstrated utility in applications such as monitoring ATP release in astrocytes and detecting serotonin in cell culture using glass nanopipettes. | 0 | Theoretical and Fundamental Chemistry |
If the diffusing particles are hindered by obstacles or pushed by a force (molecular motors, flow, etc.) the dynamics is often not sufficiently well-described by the normal diffusion model, where the mean squared displacement (MSD) grows linearly with time. Instead the diffusion may be better described as anomalous diffusion, where the temporal dependence of the MSD is non-linear as in the power-law:
where is an anomalous diffusion coefficient. "Anomalous diffusion" commonly refers only to this very generic model, and not the many other possibilities that might be described as anomalous. Also, a power law is, in a strict sense, the expected form only for a narrow range of rigorously defined systems, for instance when the distribution of obstacles is fractal. Nonetheless a power law can be a useful approximation for a wider range of systems.
The FCS autocorrelation function for anomalous diffusion is:
where the anomalous exponent is the same as above, and becomes a free parameter in the fitting.
Using FCS, the anomalous exponent has been shown to be an indication of the degree of molecular crowding (it is less than one and smaller for greater degrees of crowding). | 0 | Theoretical and Fundamental Chemistry |
Evidence suggests that NS can react with itself to reach NS, NS, and polymers of the form (NS). (NS) forms from polymerization of cyclo-NS.
Trans-NSSN results from direct dimerization of NS.
NS has been observed through photoelectron spectroscopy of vapors of the (SN), polymer, but has not yet been characterized further. Attempts to produce NS by oxidation of [PPN] [SN] were unsuccessful. Its theorized that rapid dimerization to (NS) will disproportionate irreversibly to NS and NS. | 0 | Theoretical and Fundamental Chemistry |
Maltase-glucoamylase is a membrane-bound enzyme located in the intestinal walls. This lining of the intestine forms brush border in which food has to pass in order for the intestines to absorb the food. | 1 | Applied and Interdisciplinary Chemistry |
The Hajos–Parrish–Eder–Sauer–Wiechert reaction, reported in 1971 by several research teams, is an early example of an enantioselective catalytic reaction in organic chemistry. Its scope has been modified and expanded through the development of related reactions including the Michael addition, asymmetric aldol reaction, and the Mannich reaction. This reaction has likewise been used to perform asymmetric Robinson annulations. The general scheme of this reaction follows:
This example illustrates a 6-enolendo aldolization. In the , proline catalyses an asymmetric aldol reaction. The zwitterionic character and the H-bonding of proline in the transition state determine the reaction outcome. An enamine is formed during the reaction and only one proline molecule is involved in forming the transition state.
Asymmetric synthesis of the Wieland-Miescher ketone is also based on proline. Additional reactions include aldol reactions, Mannich reaction, Michael reaction, amination, α-oxyamination, and α-halogenation.
Modifications on the basic proline structure improved the enantioselectivity and regioselectivity of the catalysis. These proline-derived auxiliaries and catalysts, including the Enders hydrazone reaction and Corey–Itsuno reduction, have been reviewed, as have MacMillan’s iminium catalysts, Miller catalysts, and CBS-oxazaborolidines.
Illustrating an enolexo intramolecular aldolization, dicarbonyl (dials,diketones) can be converted to anti-aldol products with a 10% L-proline catalyst loading.
A prominent example of proline catalysis is the addition of acetone or hydroxyacetone to a diverse set of aldehydes catalyzed by 20-30% proline catalyst loading with high (>99%) enantioselectivity yielding diol products. As refined by List and Notz, the aforementioned reaction produces diol products as follows: | 0 | Theoretical and Fundamental Chemistry |
The significance of peptide plane flips in the dynamics of the native state has been inferred in some proteins by comparing crystal structures of the same protein in multiple conformations. For example, peptide flips have been described as significant in the catalytic cycle of flavodoxin and in the formation of amyloid structures, where their ability to provide a low-energy pathway between beta sheet and the so-called alpha sheet conformation is suggested to facilitate the early stages of amyloidogenesis. Peptide plane flipping may also be significant in the early stages of protein folding. | 1 | Applied and Interdisciplinary Chemistry |
The Dewar–Chatt–Duncanson model is a model in organometallic chemistry that explains the chemical bonding in transition metal alkene complexes. The model is named after Michael J. S. Dewar, Joseph Chatt and L. A. Duncanson.
The alkene donates electron density into a π-acid metal d-orbital from a π-symmetry bonding orbital between the carbon atoms. The metal donates electrons back from a (different) filled d-orbital into the empty π antibonding orbital. Both of these effects tend to reduce the carbon-carbon bond order, leading to an elongated C−C distance and a lowering of its vibrational frequency.
In Zeise's salt KPtCl(CH)]HO the C−C bond length has increased to 134 picometres from 133 pm for ethylene. In the nickel compound Ni(CH)(PPh) the value is 143 pm.
The interaction also causes carbon atoms to "rehybridise" from sp towards sp, which is indicated by the bending of the hydrogen atoms on the ethylene back away from the metal. In silico calculations show that 75% of the binding energy is derived from the forward donation and 25% from backdonation. This model is a specific manifestation of the more general π backbonding model. | 0 | Theoretical and Fundamental Chemistry |
Like any other linear free-energy relationship established, the Swain–Lupton equation will too fail when special circumstances arise, i.e. change in the rate determining step of a mechanism or solvation structure. | 0 | Theoretical and Fundamental Chemistry |
There are two general types of methods for preparing miniemulsions:
* High-energy methods - For the high-energy methods, the shearing proceeds usually via exposure to high power ultrasound of the mixture or with a high-pressure homogenizer, which are high-shearing processes.
* Low-energy methods - For the low-energy methods, the water-in-oil emulsion is usually prepared and then transformed into an oil-in-water miniemulsion by changing either composition or temperature. The water-in-oil emulsion is diluted dropwise with water to an inversion point or gradually cooled to a phase inversion temperature. The emulsion inversion point and phase inversion temperature cause a significant decrease in the interfacial tension between two liquids, thereby generating very tiny oil droplets dispersed in the water.
Miniemulsions are kinetically stable but thermodynamically unstable. Oil and water are incompatible in nature, and the interface between them is not favored. Therefore, given a sufficient amount of time, the oil and water in miniemulsions separate again. Various mechanisms such as gravitational separation, flocculation, coalescence, and Ostwald ripening result in instability. In an ideal miniemulsion system, coalescence and Ostwald ripening are suppressed thanks to the presence of the surfactant and co-surfactant. With the addition of surfactants, stable droplets are then obtained, which have typically a size between 50 and 500 nm. | 0 | Theoretical and Fundamental Chemistry |
Gelatin is prepared from the denaturation of collagen and many desirable properties such as biodegradability, biocompatibility, non-immunogenity in physiological
environments, and easy processability make this polymer a good choice for tissue engineering applications. It is used in engineering tissues for the skin, bone and cartilage and is used commercially for skin replacements. | 1 | Applied and Interdisciplinary Chemistry |
*France–Japan: TOULOUSE–NARA, Toulouse III - Paul Sabatier University. CEMES (CNRS) and Nara Institute of Science and Technology.
*United States–Austria: Rice–Graz nanoprix, Rice University and University of Graz
*Germany: GAZE, Technische Universitat Dresden
*United States: Ohio Bobcat Nanowagon, Ohio University
*France: StrasNanocar, University of Strasbourg and Strasbourg Institute of Material Physics and Chemistry (IPCMS)
*Spain: SAN SEBASTIAN, Donostia International Physics Center and University of Santiago de Compostela
*Japan: NIMS-MANA, National Institute for Materials Science (Tsukuba)
*Spain–Sweden: NANOHISPA, IMDEA Nanoscience Institute (University of Madrid) and Linköping University | 0 | Theoretical and Fundamental Chemistry |
Unloading is the release of pressure due to the removal of an overburden. When the pressure is reduced rapidly, the rapid expansion of the rock causes high surface stress and spalling. | 1 | Applied and Interdisciplinary Chemistry |
Consider a liquid film such as a soap film suspended on a wire frame. Some force is required to stretch this film by the movable portion of the wire frame. This force is used to overcome the microscopic forces between molecules at the liquid-air interface. These microscopic forces are perpendicular to any line in the surface and the force generated by these forces per unit length is called the surface tension σ whose unit is N/m. Therefore, the work associated with the stretching of a film is called surface tension work, and is determined from
where is the change in the surface area of the film. The factor 2 is due to the fact that the film has two surfaces in contact with air. The force acting on the moveable wire as a result of surface tension effects is , where σ is the surface tension force per unit length. | 0 | Theoretical and Fundamental Chemistry |
There are several national and international bioanalytical organisations active throughout the world. Often they are part of a bigger organisation, e.g. Bioanalytical Focus Group and Ligand Binding Assay Bioanalytical Focus Group, which are both within the American Association of Pharmaceutical Scientists (AAPS) and FABIAN, a working group of the Analytical Chemistry Section of the Royal Netherlands Chemical Society. The European Bioanalysis Forum (EBF), on the other hand, is independent of any larger society or association. | 0 | Theoretical and Fundamental Chemistry |
Thujaplicinol is either of two isomeric tropolone-related natural products. They are found in tree species primarily in bark, needles, xylem, of the family of Cupressaceae like the Cupressus, Thuja, Juniperus and Thujopsis. The thujaplicinols are structurally equivalent to the thujaplicins with an additional hydroxyl group. They belong to the class of natural terpenoids having two free hydroxyl groups at C3 and C5 position.
The thujaplicinols are highly volatile compounds. It is known that the presence of such tropolones, including alpha-tropolone and its isopropyl derivatives, result in the high natural durability of wood species, such as western red cedar, juniper and cypress. | 1 | Applied and Interdisciplinary Chemistry |
HITEMP is the molecular spectroscopic database analogous to HITRAN for high-temperature modeling of the spectra of molecules in the gas phase. HITEMP encompasses many more bands and transitions than HITRAN for eight absorbers: HO, CO, NO, CO, CH, NO, NO and OH. Due to the extremely large number of transitions required for high-temperature simulations, it was necessary to provide the HITEMP data as separate files to that of HITRAN. The HITEMP line lists retain the same 160-character format that was used for earlier editions of HITRAN. There are numerous applications for HITEMP data, some examples include the thermometry of high-temperature environments, analysis of combustion processes, and modeling spectra of atmospheres in the Solar System, exoplanets, brown dwarfs, and stars. | 0 | Theoretical and Fundamental Chemistry |
When using the entropy change of a process to assess spontaneity, it is important to carefully consider the definition of the system and surroundings. The second law of thermodynamics states that a process involving an isolated system will be spontaneous if the entropy of the system increases over time. For open or closed systems, however, the statement must be modified to say that the total entropy of the combined system and surroundings must increase, or,
This criterion can then be used to explain how it is possible for the entropy of an open or closed system to decrease during a spontaneous process. A decrease in system entropy can only occur spontaneously if the entropy change of the surroundings is both positive in sign and has a larger magnitude than the entropy change of the system:
and
In many processes, the increase in entropy of the surroundings is accomplished via heat transfer from the system to the surroundings (i.e. an exothermic process). | 0 | Theoretical and Fundamental Chemistry |
The P1 plasmid has a separate origin of replication (oriL) that is activated during the lytic cycle. Replication begins by a regular bidirectional theta replication at oriL but later in the lytic phase, it switches to a rolling circle method of replication using the host recombination machinery. This results in numerous copies of the genome being present on a single linear DNA molecule called a concatemer. The end of the concatemer is cut a specific site called the pac site or packaging site. This is followed by the packing of the DNA into the heads till they are full. The rest of the concatemer that does not fit into one head is separated and the machinery begins packing this into a new head. The location of the cut is not sequence specific. Each head holds around 110kbp of DNA so there is a little more than one complete copy of the genome (~90kbp) in each head, with the ends of the strand in each head being identical. After infecting a new cell this terminal redundancy is used by the host recombination machinery to cyclize the genome if it lacks two copies of the lox locus. If two lox sites are present (one in each terminally redundant end) the cyclization is carried out by the Cre recombinase.
Once the complete virions are assembled, the host cell is lysed, releasing the viral particles. | 1 | Applied and Interdisciplinary Chemistry |
(Cholesterol epoxide hydrolase or ChEH), is located in the endoplasmic reticulum and to a lesser extent plasma membrane of various cell types but most highly express in liver. The enzyme catalyzes the conversion of certain 3-hydroxyl-5,6-epoxides of cholesterol to their 3,5,6-trihydroxy products (see Cholesterol-5,6-oxide hydrolase). The function of ChEH is unknown. | 1 | Applied and Interdisciplinary Chemistry |
Measurement of VOCs from the indoor air is done with sorption tubes e. g. Tenax (for VOCs and SVOCs) or DNPH-cartridges (for carbonyl-compounds) or air detector. The VOCs adsorb on these materials and are afterwards desorbed either thermally (Tenax) or by elution (DNPH) and then analyzed by GC-MS/FID or HPLC. Reference gas mixtures are required for quality control of these VOC-measurements. Furthermore, VOC emitting products used indoors, e.g. building products and furniture, are investigated in emission test chambers under controlled climatic conditions. For quality control of these measurements round robin tests are carried out, therefore reproducibly emitting reference materials are ideally required. Other methods have used proprietary Silcosteel-coated canisters with constant flow inlets to collect samples over several days. These methods are not limited by the adsorbing properties of materials like Tenax. | 0 | Theoretical and Fundamental Chemistry |
If a still removes 99% of impurities from water (leaving .01 the original amount of impurities), a cascade of three stills will leave (1-0.99) = 0.000001 = 0.0001% the amount of impurities (99.9999% removed). | 1 | Applied and Interdisciplinary Chemistry |
Two discoveries led to the development of glycosynthase enzymes. The first was that a change of the active site nucleophile of a glycosidase from a carboxylate to another amino acid resulted in a properly folded protein that had no hydrolase activity.
The second discovery was that some glycosidase enzymes were able to catalyze the hydrolysis of glycosyl fluorides that had the incorrect anomeric configuration. The enzymes underwent a transglycosidation reaction to form a disaccharide, which was then a substrate for hydrolase activity.
The first reported glycosynthase was a mutant of the sp. β-glucosidase / galactosidase in which the nucleophile glutamate 358 was mutated to an alanine by site directed mutagenesis. When incubated with α-glycosyl fluorides and an acceptor sugar it was found to catalyze the transglycosidation reaction without any hydrolysis. This glycosynthase was used to synthesize a series of di- and trisaccharide products with yields between 64% and 92%. | 0 | Theoretical and Fundamental Chemistry |
Miniemulsions have wide application in the synthesis of nanomaterials and in the pharmaceutical and food industries. For example, miniemulsion-based processes are, therefore, particularly adapted for the generation of nanomaterials. There is a fundamental difference between traditional emulsion polymerisation and a miniemulsion polymerisation. Particle formation in the former is a mixture of micellar and homogeneous nucleation, particles formed via miniemulsion however are mainly formed by droplet nucleation. In the pharmaceutical industry, oil droplets act as tiny containers that carry water-insoluble drugs, and the water provides a mild environment that is compatible with the human body. Moreover, nanoemulsions that carry drugs allow the drugs to crystallize in a controlled size with a good dissolution rate. Finally, in the food industry, miniemulsions can not only be loaded with water-insoluble nutrients, such as beta-carotene and curcumin, but also improve the nutrients' digestibility. Miniemulsions are also used in the creation of cannabinoid infused beverages and foods. Emulsifying cannabiniods has shown to increase bioavailability and digestion time. | 0 | Theoretical and Fundamental Chemistry |
Water chemistry analyses are carried out to identify and quantify the chemical components and properties of water samples. The type and sensitivity of the analysis depends on the purpose of the analysis and the anticipated use of the water.
Chemical water analysis is carried out on water used in industrial processes, on waste-water stream, on rivers and stream, on rainfall and on the sea. In all cases the results of the analysis provides information that can be used to make decisions or to provide re-assurance that conditions are as expected.
The analytical parameters selected are chosen to be appropriate for the decision making process or to establish acceptable normality.
Water chemistry analysis is often the groundwork of studies of water quality, pollution, hydrology and geothermal waters.
Analytical methods routinely used can detect and measure all the natural elements and their inorganic compounds and a very wide range of organic chemical species using methods such as gas chromatography and mass spectrometry. In water treatment plants producing drinking water and in some industrial processes using products with distinctive taste and odours, specialised organoleptic methods may be used to detect smells at very low concentrations. | 0 | Theoretical and Fundamental Chemistry |
Nuclear magnetic resonance (NMR) spectroscopy is known as the most widely applied and “one of the most powerful techniques” for the sequence analysis of synthetic copolymers. NMR spectroscopy allows determination of the relative abundance of comonomer sequences at the level of dyads and in cases of small repeat units even triads or more. It also allows the detection and quantification of chain defects and chain end groups, cyclic oligomers and by-products. However, limitations of NMR spectroscopy are that it cannot, so far, provide information about the sequence distribution along the chain, like gradients, clusters or a long-range order. | 0 | Theoretical and Fundamental Chemistry |
In order for proper gene expression to occur, transcription must stop at specific sites. Two termination mechanisms are well known:
*Intrinsic termination (also called Rho-independent termination): Specific DNA nucleotide sequences signal the RNA polymerase to stop. The sequence is commonly a palindromic sequence that causes the strand to loop which stalls the RNA polymerase. Generally, this type of termination follows the same standard procedure. A pause will occur due to a polyuridine sequence that allows the formation of a hairpin loop. This hairpin loop will aid in forming a trapped complex, which will ultimately cause the dissociation of RNA polymerase from the template DNA strand and halt transcription.
*Rho-dependent termination: ρ factor (rho factor) is a terminator protein that attaches to the RNA strand and follows behind the polymerase during elongation. Once the polymerase nears the end of the gene it is transcribing, it encounters a series of G nucleotides which causes it to stall. This stalling allows the rho factor to catch up to the RNA polymerase. The rho protein then pulls the RNA transcript from the DNA template and the newly synthesized mRNA is released, ending transcription. Rho factor is a protein complex that also displays helicase activities (is able to unwind the nucleic acid strands). It will bind to the DNA in cytosine rich regions and when RNA polymerase encounters it, a trapped complex will form causing the dissociation of all molecules involved and end transcription.
The termination of DNA transcription in bacteria may be stopped by certain mechanisms wherein the RNA polymerase will ignore the terminator sequence until the next one is reached. This phenomenon is known as antitermination and is utilized by certain bacteriophages. | 1 | Applied and Interdisciplinary Chemistry |
Pesticides can be classified by target organism (e.g., herbicides, insecticides, fungicides, rodenticides, and pediculicides – see table),
Biopesticides according to the EPA include microbial pesticides, biochemical pesticides, and plant-incorporated protectants.
Pesticides can be classified into structural classes, with many structural classes developed for each of the target organisms listed in the table. A structural class is usually associated with a single mode of action, whereas a mode of action may encompass more than one structural class.
The pesticidal chemical (active ingredient) is mixed (formulated) with other components to form the product that is sold, and which is applied in various ways. Pesticides in gas form are fumigants.
Pesticides can be classified based upon their mode of action, which indicates the exact biological mechanism which the pesticide disrupts. The modes of action are important for resistance management, and are categorized and administered by the insecticide, herbicide, and fungicide resistance action committees.
Pesticides may be systemic or non-systemic. A systemic pesticide moves (translocates) inside the plant. Translocation may be upward in the xylem, or downward in the phloem or both. Non-systemic pesticides (contact pesticides) remain on the surface and act though direct contact with target organism. Pesticdes are more effective if they are systemic. Systemicity is a prerequisite for the pesticide to be used as a seed-treatment.
Pesticides can be classified as persistent (non-biodegradable) or non-persistent (biodegradable). A pesticide must be persistent enough to kill or control its target but must degrade fast enough not to accumulate in the environment or the food chain in order to be approved by the authorities. Persistent pesticides, including DDT, were banned years ago, an exception being spraying in houses to combat malaria vectors. | 1 | Applied and Interdisciplinary Chemistry |
Not like the grafting from and grafting to approach which can conjugate several polymers onto one protein core, the grafting through approach enables several proteins to connect to one polymer chain due to the multivalent nature of protein. | 1 | Applied and Interdisciplinary Chemistry |
Carbon nucleophiles such as Grignard reagents, convert acyl chlorides to ketones, which in turn are susceptible to the attack by second equivalent to yield the tertiary alcohol. The reaction of acyl halides with certain organocadmium reagents stops at the ketone stage. The reaction with Gilman reagents also afford ketones, reflecting the low nucleophilicity of these lithium diorganocopper compounds. | 0 | Theoretical and Fundamental Chemistry |
Joseph Burchenal, at Memorial Sloan-Kettering Cancer Center in New York, with Farber's help, started his own methotrexate study and found the same effects. He then decided to try to develop anti-metabolites in the same way as Farber, by making small changes in a metabolite needed by a cell to divide. With the help of George Hitchings and Gertrude Elion, two pharmaceutical chemists who were working at the Burroughs Wellcome Co. in Tuckahoe, many purine analogues were tested, culminating in the discovery of 6-mercaptopurine (6-MP), which was subsequently shown to be a highly active antileukemic drug. | 1 | Applied and Interdisciplinary Chemistry |
Phytochemistry is the study of phytochemicals, which are chemicals derived from plants. Phytochemists strive to describe the structures of the large number of secondary metabolites found in plants, the functions of these compounds in human and plant biology, and the biosynthesis of these compounds. Plants synthesize phytochemicals for many reasons, including to protect themselves against insect attacks and plant diseases. The compounds found in plants are of many kinds, but most can be grouped into four major biosynthetic classes: alkaloids, phenylpropanoids, polyketides, and terpenoids.
Phytochemistry can be considered a subfield of botany or chemistry. Activities can be led in botanical gardens or in the wild with the aid of ethnobotany. Phytochemical studies directed toward human (i.e. drug discovery) use may fall under the discipline of pharmacognosy, whereas phytochemical studies focused on the ecological functions and evolution of phytochemicals likely fall under the discipline of chemical ecology. Phytochemistry also has relevance to the field of plant physiology. | 1 | Applied and Interdisciplinary Chemistry |
A bioassay is a biochemical test to estimate the potency of a sample compound. Usually this potency can only be measured relative to a standard compound. A typical bioassay involves a stimulus (ex. drugs) applied to a subject (ex. animals, tissues, plants). The corresponding response (ex. death) of the subject is thereby triggered and measured. | 1 | Applied and Interdisciplinary Chemistry |
The λ (lambda) universality class is a group in condensed matter physics. It regroups several systems possessing strong analogies, namely, superfluids, superconductors and smectics (liquid crystals). All these systems are expected to belong to the same universality class for the thermodynamic critical properties of the phase transition. While these systems are quite different at the first glance, they all are described by similar formalisms and their typical phase diagrams are identical. | 0 | Theoretical and Fundamental Chemistry |
Krige is originally a physical chemist by training, earning a PhD from the University of Pretoria in the subject. After earning a PhD in philosophy at the University of Sussex, in the United Kingdom in 1979, Krige's intellectual career has been in the history of science and technology, including notable efforts within the project to write the history of CERN and the European Space Agency in the 1980s and 1990s. His main focus is on the place of science and technology in the foreign policies of governments both intra-European and between the U.S. and Western Europe in the cold war.
In 2000, Krige became a professor at Georgia Institute of Technology's School of History and Sociology.
As a Francis Bacon Award recipient, Krige became a visiting professor at Caltech's Division of Humanities and Social Science. | 0 | Theoretical and Fundamental Chemistry |
A molecular demon or biological molecular machine is a biological macromolecule that resembles and seems to have the same properties as Maxwells demon. These macromolecules gather information in order to recognize their substrate or ligand within a myriad of other molecules floating in the intracellular or extracellular plasm. This molecular recognition represents an information gain which is equivalent to an energy gain or decrease in entropy. When the demon is reset i.e. when the ligand is released, the information is erased, energy is dissipated and entropy increases obeying the second law of thermodynamics. The difference between biological molecular demons and the thought experiment of Maxwells demon is the latter's apparent violation of the second law. | 0 | Theoretical and Fundamental Chemistry |
Pharmacometabolomics, also known as pharmacometabonomics, is a field which stems from metabolomics, the quantification and analysis of metabolites produced by the body. It refers to the direct measurement of metabolites in an individual's bodily fluids, in order to predict or evaluate the metabolism of pharmaceutical compounds, and to better understand the pharmacokinetic profile of a drug. Alternatively, pharmacometabolomics can be applied to measure metabolite levels following the administration of a pharmaceutical compound, in order to monitor the effects of the compound on certain metabolic pathways(pharmacodynamics). This provides detailed mapping of drug effects on metabolism and the pathways that are implicated in mechanism of variation of response to treatment. In addition, the metabolic profile of an individual at baseline (metabotype) provides information about how individuals respond to treatment and highlights heterogeneity within a disease state. All three approaches require the quantification of metabolites found in bodily fluids and tissue, such as blood or urine, and can be used in the assessment of pharmaceutical treatment options for numerous disease states. | 1 | Applied and Interdisciplinary Chemistry |
In September 1951, H. S. Gutowsky, D. W. McCall, and C. P. Slichter reported experiments on , , and , where they explained the presence of multiple resonance lines with an interaction of the form .
Independently, in October 1951, E. L. Hahn and D. E. Maxwell reported a spin echo experiment which indicates the existence of an interaction between two protons in dichloroacetaldehyde. In the echo experiment, two short, intense pulses of radiofrequency magnetic field are applied to the spin ensemble at the nuclear resonance condition and are separated by a time interval of τ. The echo appears with a given amplitude at time 2τ. For each setting of τ, the maximum value of the echo signal is measured and plotted as a function of τ. If the spin ensemble consists of a magnetic moment, a monotonic decay in the echo envelope is obtained. In the Hahn–Maxwell experiment, the decay was modulated by two frequencies: one frequency corresponded with the difference in chemical shift between the two non-equivalent spins and a second frequency, J, that was smaller and independent of magnetic field strength ( = 0.7 Hz).
Such interaction came as a great surprise. The direct interaction between two magnetic dipoles depends on the relative position of two nuclei in such a way that when averaged over all possible orientations of the molecule it equals to zero.
In November 1951, N. F. Ramsey and E. M. Purcell proposed a mechanism that explained the observation and gave rise to an interaction of the form I·I. The mechanism is the magnetic interaction between each nucleus and the electron spin of its own atom together with the exchange coupling of the electron spins with each other.
In the 1990s, direct evidence was found for the presence of J-couplings between magnetically active nuclei on both sides of the hydrogen bond. Initially, it was surprising to observe such couplings across hydrogen bonds since J-couplings are usually associated with the presence of purely covalent bonds. However, it is now well established that the H-bond J-couplings follow the same electron-mediated polarization mechanism as their covalent counterparts.
The spin–spin coupling between nonbonded atoms in close proximity has sometimes been observed between fluorine, nitrogen, carbon, silicon and phosphorus atoms. | 0 | Theoretical and Fundamental Chemistry |
Ca plays an important role in nodule formation in legumes. Nitrogen is an essential element required in plants and many legumes, unable to fix nitrogen independently, pair symbiotically with nitrogen-fixing bacteria that reduce nitrogen to ammonia. This legume-Rhizobium interaction establishment requires the Nod factor that is produced by the Rhizobium bacteria. The Nod factor is recognized by the root hair cells that are involved in the nodule formation in legumes. Ca responses of varied nature are characterized to be involved in the Nod factor recognition. There is a Ca flux at the tip of the root hair initially followed by repetitive oscillation of Ca in the cytosol and also Ca spike occurs around the nucleus. DMI3, an essential gene for Nod factor signaling functions downstream of the Ca spiking signature, might be recognizing the Ca signature. Further, several CaM and CML genes in Medicago and Lotus are expressed in nodules. | 1 | Applied and Interdisciplinary Chemistry |
The process of space corrosion is being actively investigated. One of the efforts aims to design a sensor based on zinc oxide, able to measure the amount of atomic oxygen in the vicinity of the spacecraft; the sensor relies on drop of electrical conductivity of zinc oxide as it absorbs further oxygen. | 1 | Applied and Interdisciplinary Chemistry |
Fretting decreases fatigue strength of materials operating under cycling stress. This can result in fretting fatigue, whereby fatigue cracks can initiate in the fretting zone. Afterwards, the crack propagates into the material. Lap joints, common on airframe surfaces, are a prime location for fretting corrosion. This is also known as frettage or fretting corrosion. | 1 | Applied and Interdisciplinary Chemistry |
Subdivisions of inorganic chemistry are numerous, but include:
*organometallic chemistry, compounds with metal-carbon bonds. This area touches on organic synthesis, which employs many organometallic catalysts and reagents.
*cluster chemistry , compounds with several metals bound together with metal-metal bonds or bridging ligands.
*bioinorganic chemistry, biomolecules that contain metals. This area touches on medicinal chemistry.
*materials chemistry and solid state chemistry, extended (i.e. polymeric) solids exhibiting properties not seen for simple molecules. Many practical themes are associated with these areas, including ceramics. | 0 | Theoretical and Fundamental Chemistry |
The use of zinc chloride as a flux, sometimes in a mixture with ammonium chloride (see also Zinc ammonium chloride), involves the production of HCl and its subsequent reaction with surface oxides.
Zinc chloride reacts with metal oxides (MO) to give derivatives of the idealized formula . This reaction is relevant to the utility of solution as a flux for soldering — it dissolves passivating oxides, exposing the clean metal surface. Fluxes with as an active ingredient are sometimes called "tinner's fluid".
Zinc chloride forms two salts with ammonium chloride: and , which decompose on heating liberating HCl, just as zinc chloride hydrate does. The action of zinc chloride/ammonium chloride fluxes, for example, in the hot-dip galvanizing process produces gas and ammonia fumes. | 0 | Theoretical and Fundamental Chemistry |
There are several ways to mathematically define quasicrystalline patterns. One definition, the "cut and project" construction, is based on the work of Harald Bohr (mathematician brother of Niels Bohr). The concept of an almost periodic function (also called a quasiperiodic function) was studied by Bohr, including work of Bohl and Escanglon.
He introduced the notion of a superspace. Bohr showed that quasiperiodic functions arise as restrictions of high-dimensional periodic functions to an irrational slice (an intersection with one or more hyperplanes), and discussed their Fourier point spectrum. These functions are not exactly periodic, but they are arbitrarily close in some sense, as well as being a projection of an exactly periodic function.
In order that the quasicrystal itself be aperiodic, this slice must avoid any lattice plane of the higher-dimensional lattice. De Bruijn showed that Penrose tilings can be viewed as two-dimensional slices of five-dimensional hypercubic structures; similarly, icosahedral quasicrystals in three dimensions are projected from a six-dimensional hypercubic lattice, as first described by Peter Kramer and Roberto Neri in 1984. Equivalently, the Fourier transform of such a quasicrystal is nonzero only at a dense set of points spanned by integer multiples of a finite set of basis vectors, which are the projections of the primitive reciprocal lattice vectors of the higher-dimensional lattice.
Classical theory of crystals reduces crystals to point lattices where each point is the center of mass of one of the identical units of the crystal. The structure of crystals can be analyzed by defining an associated group. Quasicrystals, on the other hand, are composed of more than one type of unit, so, instead of lattices, quasilattices must be used. Instead of groups, groupoids, the mathematical generalization of groups in category theory, is the appropriate tool for studying quasicrystals.
Using mathematics for construction and analysis of quasicrystal structures is a difficult task for most experimentalists. Computer modeling, based on the existing theories of quasicrystals, however, greatly facilitated this task. Advanced programs have been developed allowing one to construct, visualize and analyze quasicrystal structures and their diffraction patterns. The aperiodic nature of quasicrystals can also make theoretical studies of physical properties, such as electronic structure, difficult due to the inapplicability of Bloch's theorem. However, spectra of quasicrystals can still be computed with error control.
Study of quasicrystals may shed light on the most basic notions related to the quantum critical point observed in heavy fermion metals. Experimental measurements on an Au–Al–Yb quasicrystal have revealed a quantum critical point defining the divergence of the magnetic susceptibility as temperature tends to zero. It is suggested that the electronic system of some quasicrystals is located at a quantum critical point without tuning, while quasicrystals exhibit the typical scaling behaviour of their thermodynamic properties and belong to the well-known family of heavy fermion metals. | 0 | Theoretical and Fundamental Chemistry |
By replacing the alcohol with a silane, C-glycosides can be formed. With triethylsilane (R'=H), the reaction yields a 2,3-unsaturated deoxy sugar. | 0 | Theoretical and Fundamental Chemistry |
In the presence of copper(II) chloride, methanesulfonyl chloride will add across alkynes to form β-chloro sulfones. | 0 | Theoretical and Fundamental Chemistry |
A 2D synchronous spectrum expresses the similarity between spectral of the data in the original dataset. In generalized 2D correlation spectroscopy this is mathematically expressed as covariance (or correlation).
where:
*Φ is the 2D synchronous spectrum
*ν and ν are two spectral channels
*y is the vector composed of the signal intensities in E in column ν
*n the number of signals in the original dataset | 0 | Theoretical and Fundamental Chemistry |
A bloomery is a type of metallurgical furnace once used widely for smelting iron from its oxides. The bloomery was the earliest form of smelter capable of smelting iron. Bloomeries produce a porous mass of iron and slag called a bloom. The mix of slag and iron in the bloom, termed sponge iron, is usually consolidated and further forged into wrought iron. Blast furnaces, which produce pig iron, have largely superseded bloomeries. | 1 | Applied and Interdisciplinary Chemistry |
Although, solasonine has anti-infection properties it has many adverse side effects as a steroidal glycoalkaloid. These side effects include low blood pressure, a decrease in respiratory activity, rapid heart beat etc. These side effects are the direct result of the cytotoxic properties of solasonine (at high levels) that lead to disrupted cell membranes. | 1 | Applied and Interdisciplinary Chemistry |
Trials of using algae as biofuel were carried out by Lufthansa and Virgin Atlantic as early as 2008, although there is little evidence that using algae is a reasonable source for jet biofuels. By 2015, cultivation of fatty acid methyl esters and alkenones from the algae, Isochrysis, was under research as a possible jet biofuel feedstock. | 1 | Applied and Interdisciplinary Chemistry |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.